Land Rover cruise control testing

Sean from Cornville Owner Posted   Latest   Edited  
Question
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2005 Land Rover LR3 HSE 4.4L 6-spd (6HP26)—SALAF25425A328203
P0525 - Cruise Control Servo Control Circuit Range/Performance
P0579 - Cruise Control Multi-Function Input "A" Circuit Range/Performance

I had this Land Rover in the other day, and I can't find any diagnostic info for the cruise control at all. In fact, the codes I posted are ones that the customer told me it had. When I scanned it, it had several transmission ratio codes, which he is having another shop install his used transmission next week to resolve.

Data stream shows release button normally true. If I press any button, it changes to false. resume shows true when pressed. + shows true when pressed. - stays false all the time, but does change the state of the release button. If I was to guess, I would think that there's a button problem, but I have zero information on this system.

I found wiring diagrams for the cruise, and theory of operation, but zero tests. Does someone at least have the button resistance values, so that I can test it? I told him to see if replacing the transmission will fix it. If it doesn't he will be back.

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Pat from Westfield

 

Technical Support Specialist
 

Sean, out of curiosity what year and model Land Rover?

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Sean from Cornville

 

Owner
 

Sorry, I posted the vin, but it didn't take. SALAF25425A… LR3 HSE

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Pat from Westfield

 

Technical Support Specialist
 

When you were watching the + and - button input PIDs, were you driving or sitting in a bay?

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Sean from Cornville

 

Owner
 

Both sitting in a bay, and driving. I did find in mitchell, a description for the codes, and P0525 is an internal control module software corruption, maybe just cruise disable, and P0579 is a fault with the buttons, either high resistance, open, short, or stuck.

The course of action for the P0525: Refer to the warranty procedures and policy manual if a module is suspect.

The course of action for the P0579: Refer to the electrical guides, and check the cruise control circuit between the ecm and switch. Check the switch operation, and renew/renew as necessary.

It clearly states to test the switch operation, but no test is listed anywhere in Mitchell, or Identifix.

I'm not sure how he got those codes, because I did not pull them from any computer with my Solus edge, or Autel DS808.

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